Suppose in Fiscalville there is no tax on the first $10,000 of income, but a 20 percent

Question:

Suppose in Fiscalville there is no tax on the first $10,000 of income, but a 20 percent tax on earnings between $10,000 and $20,000 and a 30 percent tax on income between $20,000 and $30,000. Any income above $30,000 is taxed at 40 percent. If your income is $50,000, how much will you pay in taxes?
Determine your marginal and average tax rates. Is this a progressive tax? Explain.